Cushioned cutter pilot



NOV. 23, 1943. N sMlTH l Y 2,334,795

Y CUSHIONED CUTTER PILOT Filed July 50,'1942 2 Sheets-Sheet l Nov. 23, 1943. N, Q sMlTH 2,334,795

CUSHIONED CUTTER PILOT Filed JulySO, 1942 2 Sheets-Sheet 2 Patented Nov. 23, 17943 I l UNITED STATES cUsnIoNEn onrtrnnrrrlozr. Nen.o.;smah,rnimaimns, Minn." f Application July so, 1942,)se17-ia1 No. 52,972 l V14 claims. My present invention relates to pilots ior'in- Y.

ternal machining tools ar1`d,rnoreV particularly,` .n

to-a cushioned cutter pilotlor use infconn'ecin a forgingcasting or'the like. n An object o'ffthe invention 's to4 provide a cusiiioned'-pilot applicable to a Vboring bar in closeV proximity to a cutter thereon," to lfnlove with the cutter'into a boreina'piece oiwork for'fst'eadying theboring bar.

Another obj-ect of the mVenOI is toproyide a Cushioned Puoi? applicable to a boringV ba'rzin close proximity to acutterjthereon; to move with the cutter into 'a here. in a piece foi work and having yielding fmeans` for engaging the wall of* the bore .and affording a .hearing-ier the boringrbar. 1 l i I Still another Y provide a vcushioned pilotg'rotatably applicable oloject offthe Yiriventionr isrftol vtion with the 'boring bar. of a machine for in'- ternallyboring', cutting `or.otherwise nishing to a predetermined diameter Valong Vor deep hole Y (cnw-5s) mations of devices hereinafter described' and defined in the claims. Y i, Y r

lIn the f accompanying drawings, whichfillusparts throughoutv the several views." 'Referring' tothe drawings? Fig, 1 is a fragmentaryview showing the in-4 vention mounted on aboringbarfdirectlyback of acutter on lthe. outer end thereof, andalso Vshowing a piece of work, to wit: a "cylindrical trate the invention, like characters indicate'like `forging or casting 'having an axial hole and .held by clamps in aY frame with its-external *diameter con'cerfl'tric with the cutter;

to a boringrbar in closefproXirni'ty-.td afcutter tlfiereon,` to'rnove Vwith-the cutter `into', a bore'in a piece of Vworlrand'` having av plurality ofcircumerentially spaced yielding members for eri`l gaging Vthe wall ofithe borexand fiictionallyY holding the pilot from4 rotating; whereby rv'the isA Vfree to rotate. y f A furtherobjectof the il'avention'istopro-A vide a cushioned pilotY forffollowingaV cutter into a bore'in a piece ofV work fto Vresist side forces `tending to move thecutte'rout ofaxial alignment, due to the cutting vaction of theV Y cutter; especially whenlcutting' through', excesf A sive stock onv one portion-of the work, such asV 1' would vdevelop in` a` forging or `al casting when .the rough Vhole therein is eccentric to 'theioutsidefdiameternof the work.Y

VAsi-,ill further object of' the inve'nticrinu isto l provide a; cushioned Vpilot for?` iollowingfa 'c iitfter intoA a-hore in apiece of 'worlandhavingja plurality 1 ofV circumferentially" spaced` padsA lthat are. independently yieldingly heldaprjectedffor engagement 'Wahine warrior ueborelandithat Y willyieldf and-pass over highspot's that `are left` pilotfaiiordsV a bearinginwhich the boring' bar Fig. 2 isv a fragmentary view and partly in horizontal section. takenon the linefZL-Eo'f Figi; "f y Fig 3 isY a View corresponding Lto Fig. 1 with the exceptiongthat'it is somewhat morefragfA mentary and that theboring bar, vcutter and pilot are projected intothe work;'

Fig. Li'is aview, partlyin plan and partly in central 'sectionjof the cushioned cutter pilot on an enlarged scale;V

5 lis ag Y partlyA in section,fof thecushioned cutter pilot, 'as shown'xinFig; er f V Fig. 6 is afragmentary vview in section'fshowing a slight modiiication' of ,the .cushionedMcut-u ter. pilot; Y

Fig. 'l is 9,perspective' view of-'thespring ref@ moved fromV thecushioned cutterigpilotshown Y in Fig. 6; and

bythe cutter .when boring, :especiallyfrough terxinaiial alignment. L .1 d y.

boring,` but at. the Vsaine*time .keeping the cutotner objects of the invention" will fb ap? parent from the following descriptiom reference Y;

being had to the 'accompanying drawings.. i

. To the .above end,.'gen'eraiiystated; the zin;

vention Lconsists of'v'thenovelf devices and coni- Said .draw l M 1 Y Y through holes' 'in the adjustable clamping 'barn 'Figsff and 9 are fragmentary views other slightinodications of thecushicned :cut-1V ter pilot. j. Y fflhe numeral I`` indicates; fragmentarily, ai skeleton trarne, having upper Vand lower, :clamps `I Iy for holding a piece of work' to .be machined, Each clamp II comprisesa fixed barl I2 and a cooperatingfjmovaple bar I3`, said .bars being The movable vclampinghar I3m is" adjustably con- I2 'by Va vpair laterally spaced 1 inA a horizontal plane.

fectedV .to the'iixedclamping bar l of; draw [studs I' and nuts `I5 applied to the;

; screw-threaded'cuter end portions of said studs..V Thesefstuds I'are rigidly securedrto-'theV fixed.

clamping` 'har `I2 by. screw-threaded"engage-Y studs id 4 extend loosely I 3 and the nuts. I 5 thereon impinge against' the` outer'. ff'aceofV saidbar I2 vand thereby limit the rnovement'of Vthe clamping bari?. iromlthe Y clamping har I2. (3o-operating half-seats I6; l in the'formof arcs of a circle are formedjin the opposing faces ofthe "clamping-bars I2 "andV Ti oFF-rc partly inf plan View, partly gin sideelevation and Y2 Y Y y 2,334,795 @eff I3 of each clamp II, between the studs I4 of the respective pair. A bushing I'I` is secured in the frame top member I8 in axial alignment withV the half-seats I6.

A long cylindrical forging or casting I9, hereinafter referred to as a piece of work, isrheld by the clamps I I in an upright position with its external diameter concentric to the bushing II. A hole 20, which may be assumed tobe rough,Y extends axially completelythroughthe work I9. .The work I9 rests, as .its lower eend, on :fa'hprizontal ilat frame member 2I and is thereby held against downward endwise movement in the clamps I-I.` f An escape hole 22 for a cutting iluid or a coolant discharged into the holev 20 rduring cutting .oper-v ation and also for chips land.shavingsut from the work, is formed in the frame member'Z'I. 'The member 28 by a machine screw 33 which extends through a central hole in said pad and Y has The heads of the screws 33 are in recesses 34 in the pads 3E! and the tops of said heads are below the faces of the padsi) when said pads are retracted to their innermost positions. Spacing sleeves 35 on the screws 33 extend loosely through the holes in the pads 3i) and are held between seats 32. -lhe'segsp'acing sleeves 35 aiTord stops that limit the movement of the screws'33 toward the axis of the body member 28 and position the inner surfaces of the heads of said screws exactly l5 thexsamef'cl'stance from said axis. The heads of .thescrewsSS .limit the projecting movement of threaded engagement with the body member 28.

the-heads loisad screws and the bottoms of the the padsi and normally position said pads with diameter of the escape hole ZZis-.SIightlyJarger than the rough hole 2'0 in the work IIiLso'thatY the cutting fluid or the coolant, together with metal -hips .and `islfaavings carried therebyr and flowing down the wall of tlieghple-.Zwill-:be freely- Dlecipitated through the shale @22 and .away from thegwork. j l

A long uprightiboringgbar .is .fmountedgin the bushing Il for compound .rotary and-axialfeeding movements. @my the flower .gend Jportion of thebcring'bar 2.3 isfshown andfhas.mounted` on itspredueed .-taperedjower iendfpcrtion ,a/.diskelike cuttenheadM having omits periphery a plurality of-icutters 25. While.the;drawings.show acutter head :having a plurality of .cutters it will, -of course, beunderstlood .that a.cutter.head.having only afsingleecutter:,may-.berused It may befassumedgthat rthe .boring bar z23' .is mounted inga suitable machine, not shownyforjrotating and moving said Joar-axially .and v,feeding the'vcutters 25 ,to their-work. lFig. 1 ...shows the 1boring vbar 23 irl-.its uppermost position. K j` A cutting duiden-coolant issdischarged from pipes @2.6,leadingromtarry-fsuitablesource,ofsupplmfnotshowminto :the hole Zdandonto the kwaal-1 theirfaces exactly the same distance from the axis of the body member 28.

36 to .facilitatetheentrance-of thecushionedcutthereof, the cutter head 24,?the uttersand the A.cushionedpilot, as .willpresently appear.v

.The parts-.thus .far-,described arealLwell known and have been illustratedY simplysforthepurpose Qfsshowfingtthe rinvention .in .working position.

iReferiing :now i.in detail .to cushioned cutter pilot 2l', as shown in Figs. 1 to 5, inclusive, the same vincludes a .cylindri cal .body member ,v2 8. 'I his body memberis ...is rotatably 4;-rr1.ounted .on .a reduced portion of the boring bar23 ,iustback of the-cutter head2!! andnaords .a-.bearing in .which the rboring .bar 23 isfiree .to rotate, `as will .presently appear. A shoulder 29 on the boring bar 2,3, .against .which the .upper tacefof.the.pil0t 21 mpnges, `pesitively v.Incheslsaid ,pilot axially .with thelboringfbar '2.3.

Y'Ehe cushioned y.cutter .pi-lati] .further .includes a pluralitvofpyieldingly iercnlecte"d .workfensasne pads 30,as-shew tour,.circumferentially tspaced aboutthepermheiyrof.ehemdymember ze equal' distances apart. These vl.pads Sagas shown, .have thefsame width asl thebody .member ,2Bv and .their innerer-back portions El ,are .reducedin width, circumferentiallynf ...said :.member, and .mounted inetransverse :.32 in `the periphery of fthe body-member x28." '.The .fsides of backA portion sidesfofutheirespectiiie heetst-2: are .correspondingly fermedeandtheifeby :held the pad..3o;,fro'm turning'iinisaid seatfbut permitifreemevement.thereof enla-.iradiail'gline pretending strom theax-is ltof `.the

allel and the tenplot? -intothe hole .20 .and the axial move.- ment of, saidpilottherein.

Resilient rubber members .3.1 .are mounted .inf

the seats 32 iunder .the pads vA3D. and :have central holes-.through .which the spacing sleeves35 ,ex-l

tend. Primarily,the resilient .rubber vmembers 3'I are thicker than `the normal .distance between the r.pads 35 and the fbottoms offthe 4s'e'ats.32 yso that `when .assembling .the vcushioned cutter pilot 2"'I, theresilientrubber members-.31 are corn-V pressed by the pads .as they are drawn .into thefseats i 32 by-thescrewsr33. These .compressed resilientfrubber members-..31 ynormally `and 'yielda Ain-glyhold thepads iqprojectedagainst-the heads otthelscrews33. .The diameter ofi-the .body member vismeduced midway between the .pads `3I'I of :each Apair, .asfindicated-"at.38., v.to leave a pas-.- sageway 39 between the body member 23 and the wall @ofthe hole 2li-.for the'ow yof the cutting fluid-.or -theecoolant therethrough. Ahole .40, for

thegcoolant, -as .fa lubricant, extends .radially v t-hroughthe ,bodyimember .28 -fromeach passage-f way 3.9 tothegboringbar and midwaybetween the seats-Zvofeach'pair. Y

. f'lhein-Qrmalfexternarl diameter'ot'diametrically i opposite ,gpads 30 :is slightlyggreater than .the diamfeterfoffthehole $20, aszthe' same is bored rby the cutters 25 and hence the pads 30 mustbe-squeezed iImWardly-to-thef diameter of the. hole ZIIl in order to fenter itheesame. As the ,pads 30 move inward- 1y :under a vsqueezing action produced iby their entrance .into the Ihole .-2 0, they. moveY #away from the heads :of .the lscrews 33 .and compress the resilientzrubber members .31.

I Operation .-Itrnay-be assumed, forinstance, that .theJcut-z ters 25 are adjusted to boreJthe hole-.20 in .ther

` work Ill-to .adiameter of 4.375 .andthat .theexternal .norma1.,diameter ,of g. diametrically Y opposite pads :is 4.377. Obviously, thewinitialboring' offthe .'.ho1e..2.0 takes place before the .cushioned cuttenpilotlZI is .broughtinto an .operative ,posi-Y tionbyaxialjfeeding movement of .the boring bar I 233.V But vas .this initialboring takes place -relaf rtively closeto thelbushing IT, saidl bar Vis securely heldito resistfforcestending to'movethe same out of 'ajxial alignment. "In -other words, 'the `cutter bar and the cutters are wel-lsupported at the-start of -the flooring operation but 1ose--thi-ssupport fas the-cutters workdeepenintothe bore,=and therefordere-fout of Icontrol tto resist the side cutting forces{and-whippingunlesse:piloter the typev beve described-is .used AsLth'ejpilot l2;I direct- The faces ofthe. pads'il, at the ends thereof, a-re chamfered at" 1y back Vof thecutter head124;` verylittle" boring takes vplace before the pilot, 21 is Vbrought into'lv aanwas' n engagement Vwith the upper endl` of the'work" |9.`

bore the chamfe'rs`36,VV by theirengagement with the wall of bore, carn'fithe` pads SDQ-inWard-'l'with a squeezing actionaandthereby moves'said `pads away from the heads of the screws'lilV and corn- As-the pilotZTifollowsthe,cutterhead 2`4 into the p and lwould be the same; asnot'having any pilot ati -1 vMy cushioned cutter-'pilot is `particularly valu-2- fable whenl using a carbide tippedroutter, sinceY sucha cutter 'iis-operated ,at high cutting speed andA requiiesaV Veryrigidsetup 1in order to avoidt chattering which is very detrimental to carbide.

" Without a pilotv as described,Vv the boringhar presses the.resilientlrubbermember 31.` By the. Y

time the pilot 21 is within the bore 20, the`ex-f ternal diameter between diametrijcally opposite pads 30 has been -reduced-002 or,-in1other words, to the diameter-of the`bore 20.

The frictional engagement f the pads 3l! witht the'wall ofthe boret'Zl) `will holdthe pilot 21 from rotating about its axis and said pilot affords; a` bearingin`which the'boring bar-23 is rotated."

ThepilotZ'l, due to its `constatut *proximity'to the cutter head 24, holds the respective end of the boring bar 23 in axial alignment'andresists side forces, tending to move said bar and hence the cutter'head 2Q out "axial alignment, dueto" would beforcedto one side, due tohard'spots in the material, or uneven stock, building `up an ex cessive pressure on the opposite ,cutter which Y would Acausefit to chip', And as `the .tool revolves,

the cuttingwaction ofV the cutters `25,fespecially1V when cutting through excessive stock on one portion of the work, suchas would develop ina forging or a ,casting :when the roughhole'therein is Y eccentric tothe outside v diameter of the work. l 9."

The pads 30, as the pilotjZTV follows'the cutter Vit, 1in? turn, 'comes in Vcontact withthe uneven stock, and due-to the fact that it has lost its cut-A ting edge, builds up a greater'pressure than be- Y iore; andinallyibreaking the cutters. Itis obvi- Aous` that this cannot be avoidedsince the cutter visinthe Work, and itis, impossible to see just what is g-oingfon until it is too late, and thebar is either snapped, or the machine is damaged.

=It is also impossible to' use a stem pilot on the end ofthe boring bar ahead of the cutter, as thislwould double the-lengthof the setup and still would' be'` of no value sincethe diameter of the pilot wouldlce away out of proportion to its length and'thus lose its effectiveness. .n Y n Referring nowin `detailgto the modifications head 24 into the bore` 20, will independently yield,

during theirdownwardlyslidingrnovement on the wall'of the bore and .pass over any high spots that are leftby the `cuttersiZliuwhenboring, especially cutter head 1 axial alignmentn Obviously, Vthe farther the cutter head 24 moves yaway fromV the bushing Hjand into the bore 2f), the greater the need Otthe pilot 21.', Y

, The resilient members'lpermit diametrically opposite Vpadsll to be contraetedtoan externalv diameter of 4.370,-befores'aid padswouldcome rough boring, but at the same timekeeping theV i tiallyliketheillustrations shown in Figs- 4 and 5 except forfthe resilient members Afor projecting @netpass 1n sig.v 6, the pilot 4| is considerably wider/than-thepilot 2l and its pads 42, only one of which `is shown, are secured to the body member, 43 by two machine screws d. The pad 42 is yieldinglyvlield projected vbya widev flat steel spring 45. that is formed on reverse longitudinalf` l Vlypspacedcurves, see, Fig.- 7. [This spring 45 has three-pointcontact Withrtherpad 42V and four-` pointconrtact with the-bottom `of the seatll in into direct contact with the periphery of the body member 28foutwardly of the seats V32 andl at this time, the pilot,2.1.would, act Yasa solidi` structure. Y -In this respecta trifle extra clearance, in addition to-the 4.370betweenthe pads 3Q and the body member 21 is provided so that the pilot 2.1will not wedge intheholeV v2Q. is an irnportant feature since itf'would actas a safeguardv in case of a defective icutter giving away and.

would keep the boring bar 23 in control andA pre;-i l

vent damage to anvof lthe workingparts. In normal operations, the` pads 3,0,will not becompressed to a degree inwhich thepilot 21 acts as a solid structure.,v Y

bar designed to carry, the saine or i't'may be aoplied to4 an old .or existing boringr barsimply by turning down the end portion of Vsaid bar, .inst back of the cutter head 24 to receive saidpilot, Thislis one of the many advantagesof mycushi,

`ionen ,cutter pilot as it makesY it possibleior a g manufacturer to change hislekisting 'machinery Y at an extremely small costaud withoutdelav to f i do accurate deep vhole boring, thus avoiding. long delayand new expensive eouiprneni'.,V While 'the which saidpad ismountedV Spacing sleeves 41 on the screws d extend through elongated holes 4B inthe spring 45 and permitthe required yielding action of said spring. j 'The holes QS, in the body memberjli fora-lubricant corresponds to the hole AB.A The recesses f orthe heads of the screws @i4-and the ohamfered edges o f the padz42 are designatedby the numerals 5 2 and 5l, respec-, tively.`v Y l i,

The passageways 3S permit the free flow of they coolant, discharged into `,thelboreZilromV theY pipesrZF, down the wallof said bore, aroundthel cutter headY 2li, the cutters 25 and the pilot 21 and carry with it pieces of metal and shavingswfrom The pilot 21 may beV applied V to newhling, f

pilot 21 is shown in connection with'fa vertically f disposed boring bar, it is equally well adapted for,4

use on a fhorizontallydisposed boringgbar.

Itis well known that a'solid ornon-yielding type of pilot would not work under the Vconditions heretofore described, .since it would wedge inlthe bore and causeserious 'damage to the machinel To reduce the diameter ofV a solid type pilot to prevent Vvwedging would destroy its eiectiveness the cutters 25 andfallow them to beV precipitated `tree kfrom the worl; through the escapeV hole 22;

, 'IhepilotV shownin Fig. 8 is the sameas the Y pilot 4 I shown in FigL, and Acorresponding .parts are :given:` the samejreference numerals followed bya prime with the exceptionof lthe resilient rubber member 65 for projecting the pad 42.

This resilient rubber-member i5 is the same as i" the resilient rubber member4 S'ljexcept that the bottom ofthe seat '6E' is spot drilled at 52 under .the rubber memberl, thus making it possibleto cient resiliency.VV Y 'i In Fig. 9, the structure usea thinner piecerof rubber and still get suiiis the same as; that I shown in Figs. 4 and swish tneexception that a coiled spring 53 is used inlpla'ce of the resilient rubber-member 31.7.. Parts of the pilot shown in I Fig. 8 are given the'same reference numerals Aas c, correspondingpartsin Figs. LlV and 5 followed by theletter'a. An annularjchannel 54 is vformed inthe body member 26a for the coiled spring 53.

The'wide Vpa'dsshown in Figs. 6 `and 8 give a f longer bearing Lon the respective .body mem'bjers and hence the boring bar and they also give .a lenger'bearing on'thevwall of the boreandftherefore-:would cut Adown wearlconsiderably.

The 'drawings .illustrate :a commercial forni pf the '.invention, but-'it will be -understoodithat the samevis capable-of certain modications `as to l detailsv of construction, arrangement and combi-v nation Kofi-parts `within :the scope of :the invention herein disclosed. Y

..-1. 'A 'boring bar having a cushionedzcutterpilot in rclose prcximityzto its :cutter and includinga plurality of circumferentially spaced members forv contactLw-iththe walliof a bore in a piecerof work, 'and resilient means under strain-to pro- V ject said "nflernloers` ."12." A cushioned cutter pilot rotatablyrappli'cablefto va boringbar in close proximity to a' Acutter thereon, :saidpilot `comprising a body member having Aa :plurality of'circumferentially spaced mem-bers vvforscontaetwith `the wallof a :bore in a peee-of'work, and .resilient means .understrain to prejectsaid lmembers. f

L3. .lA-cushioned cutter'pilot applicable to a bori ing bar inclose vproximity to av-cutter thereon,

saidpilot comprising a body member -having a pluralityof-circumierentially spaced members for Contact with the -wall' of a 'bore in a piece of workfandresilient means under strainto pro/ject projecting movement of Lthe members to a Vdiameterslightly greater Itina/nthe diameter of the bore. v A -f =5. TheJst-ructure defined in claim 3 further includingstop means for Vlimiting Ythe lmaximum projecting movement of the members toa 'diameter slight-ly greater `than the `diameter'of the bere', said members having cam-acting surfaces for contact with Ythe work at the entrance 'rim of 4*the bore for contracting the rmembers t0 the diameter` of the bore during `movement 'o the pilot-into the bore. -A6.1-A cushioned'cutterfpilot applicable to a-boring zbar `in vclose proximity to a cutter thereon, said pilot comprising a body member having at its periphery a plurality vof circumferentiallyv :8..Afcushionedncutter pilot rotatably applicable to'fa boring bar in close proximity to a -cutter thereonfsaid pilot` comprising a ,body member havingin its `peripheryaplnrality of. circumferem tially spaeedseatapads mounted inthe seatsfor projecting-:movement to engage the wall. of a .boreA in'afpiece .offworln :means for limiting the -project,

ing movement lof the pads to .a :diameter slightly greater than thediameterpf thebore, and resilientmeans in the seats under strain :tofprojectlthej pads.

9. The structuredeinedinclaimiffurther cluding cam-acting surfaceson `thepads for con,-

tact @with the work at the :rimlof the vbore vfor contracting the pads to the diameter :of therzbere during l movementl of the pilot into the bore. 110. A `Cushioned utter pilot rotatably: applibershoulders ron vthe screwsengagi-ng therbody member and positioning :the innerlsurfaees. of the headsof ythe .screws allthesame radial distance from 4the 4axis .of ,the pilot, Asaid .pads .normally engaging `.the Ainner surfaces ,of .the V heads .of l.the screwsand positioning ,the padsiwth their .faces all the same radial distance Lfrom the axis of the pilot, the normal diameter .,of the pads beingv slightly greater than thediarneter kof .the borein 1 theework, theheadsof the `safer/.s .beine nlreeSSQS in thepads, and lresilient means in @the seats under the pads and under strain to Aproject thepadsand hold the same aeainstthe beads ofthe-screws- A12.. The Structure dened in Claim 710.111 which the resilientnieans for eachwpadLis la piece of rubber held under compression pad.

13; 'Thefstnicmre defined in claims ni which the diameter of the body member between the members lis reduced `in diameter to alford passageways between thefpilot and the Waller the bore foracoolant. 14. The structure defined in claim 8 in which the Ydiarne'ter of the vb ooly member between Vthe seats is reduced in diameter Lto affordrpassageways between the pilot and the wall ofv the bore for a coolantf v i .the entran@ Qf the Pilat by the respect 

